To read the full-text of this research, you can request a copy directly from the authors.
Abstract
Populations of all species of sawfish have been depleted worldwide, and sawfish are now absent from much of their historic range. Much of the historic sawfish capture and encounter data does not provide information useful for species identification, and so cannot be used to reconstruct the historic ranges of the different species. For a long time, these data were also not easily accessible, as they were not digitised. Thus historic populations and distribution ranges of the
different species could have been underestimated. Here, we examine historical newspaper articles (n ¼ 237) from the Australian National Library’s online database ‘Trove’, that were found by searching for the generic term ‘sawfish’.
Articles were examined for information that could be relevant to sawfish biology and distribution, as outlined in the IUCN’s Sawfish Conservation Strategy, such as date of capture, circumstance of capture, location, animals’ weight and length, and potential species identifiers. One of the articles is presented in detail as it outlines a capture of Pristis pristis outside of the currently described range of this species, by over 800 km. This evidence highlights the need for a global examination of historical print resources, which use generic terminology to report sawfish encounters. Examination of global news resources may help provide greater understanding of the full historic range of sawfishes, and allow a more accurate estimation of areas in which they no longer occur.
The rapid expansion of human activities threatens ocean-wide biodiversity. Numerous marine animal populations have declined, yet it remains unclear whether these trends are symptomatic of a chronic accumulation of global marine extinction risk. We present the first systematic analysis of threat for a globally distributed lineage of 1,041 chondrichthyan fishes-sharks, rays, and chimaeras. We estimate that one-quarter are threatened according to IUCN Red List criteria due to overfishing (targeted and incidental). Large-bodied, shallow-water species are at greatest risk and five out of the seven most threatened families are rays. Overall chondrichthyan extinction risk is substantially higher than for most other vertebrates, and only one-third of species are considered safe. Population depletion has occurred throughout the world's ice-free waters, but is particularly prevalent in the Indo-Pacific Biodiversity Triangle and Mediterranean Sea. Improved management of fisheries and trade is urgently needed to avoid extinctions and promote population recovery.
Within the Great Barrier Reef World Heritage Area in Queensland, Australia, lack of information on the distribution of sawfishes presents difficulty for informed management of their habitats and populations. This study aims to provide insights into the historical and current distributions through analysis of sawfish by-catch records from the Queensland Shark Control Program (QSCP), which has protected bathers since 1963 by targeting large sharks. Sawfishes have been caught in 8 of the 10 areas where the QSCP has been active. A total of 1450 captures of sawfishes (all 4 species known from Australia) were reported from 1963 to August 2016, with most ( > 99%) in the 4 most northern areas; Cairns, Townsville, Mackay, and Rockhampton. Sawfishes were mainly captured in gillnets. Most (95.4%) animals were alive when the gear was checked. In Townsville and Rockhampton, standardised sawfish captures have declined over the years. No sawfish captures in QSCP gear have been recorded in 3 areas (Cairns, Townsville, Rockhampton) since gillnets were banned there, but in Mackay, where gillnets are still used, only 4 animals have been caught since 1999. It is recommended that QSCP contractors take more detailed data of future sawfish captures, and that contractors and fishers receive training on releasing sawfishes swiftly and with minimal damage. Moreover, as the use of gillnets in the QSCP has been decreasing over the years, fisheries-independent studies of current sawfish distributions are required.
Sawfishes are the most endangered cartilaginous fishes on the planet. Their external morphology facilitates entanglement in fishing nets and their K-selected life history hinders the recovery of exploited populations. The Eastern Amazon coast (EAC) is known to be an area where sawfishes occur in Brazil, but few studies have been conducted in the area to better understand their biology and ecology. The present study reports sawfish captures along the coast of Brazil’s second largest state. Data were collected from interviews with fishermen, a literature review, and media reports. In total, 23 captures were recorded between 1984 and 2016. Records include adults, a pregnant female with near-term embryos, juveniles, and young-of-the-year specimens. Most catches were reported in the Canal do Navio, an area under strong human pressure. Sawfish saws are valuable items and, for many anglers in precarious economic and social situations, high market prices eclipse the fishing prohibitions laid down under federal laws. Urgent research is required to understand sawfishes’ life history, identify their critical habitats, and effectively manage and conserve these species along the EAC.
Intergenerational loss of information about the abundance of exploited species can lead to shifting baselines, which have direct consequences for how species and ecosystems are managed. Historical data provide a means of regaining that information, but they still are not commonly applied in marine conservation and management. Omission of relevant historical information typically results in assessments of conservation status that are more optimistic, recovery targets that are lower, and fisheries quotas that are higher than if long-term data were considered. Here, we review data and methods that can be used to estimate historical baselines for marine species including bony fishes, sharks, turtles, and mammals, demonstrate how baselines used in management change when historical data are included, and provide specific examples of how data from the past can be applied in management and conservation including extinction risk assessment, recovery target setting, and management of data-poor fisheries. Incorporating historical data into conservation and management frameworks presents challenges, but the alternative—losing information on past population sizes and ecological variability—represents a greater risk to effective management of marine species and ecosystems.
Pristis microdon, P. zijsron, P. clavata and Anoxypristis cuspidata are distributed throughout the Queensland section of the Gulf of Carpentaria, Australia. In a survey of the four species, Anoxypristis cuspidata was the most abundant and was recorded in both the inshore and offshore set net fisheries. The size distribution and catch locations of A. cuspidata suggest that the inshore area to a depth of 10m may be the preferred habitat for juveniles of this species, while adults primarily occur offshore. Pristis microdon, P. zijsron and P. clavata were recorded only in the inshore fishery with catches dominated by immature animals. Pristis microdon was caught in the inshore fishery late in the monsoonal wet season (February to April) and inhabited both freshwater and estuarine environments. Pristis zijsron occurred only on the sand and mud flats outside river mouths whilst P. clavata inhabited both the sand and mud flats and upstream estuarine habitats. Observations on reproductive staging and the capture of neonate specimens suggest that in all four pristids, pupping occurred through the wet season until the beginning of the dry season in May. A seasonal set net closure for the barramundi, Lates calcarifer and shark fisheries, which has been in place since 1980 in Queensland Gulf waters, therefore offers a measure of protection to breeding female sawfish and their offspring.
Darling Downs Gazette
Jun 1902
3
Anon
Anon. (1902). A monster sawfish. Darling Downs Gazette 17 June 1902, p. 3.
Harpooned. 18 ft sawfish caught at Manly. The Daily Telegraph
Mar 1923
1
Anon
Anon. (1923). Sawfish weighing 21/2 tons. The Register 10 March 1923, p. 5.
Anon. (1926a). Harpooned. 18 ft sawfish caught at Manly. The Daily
Telegraph 11 October 1926, p. 1.
An 18 foot sawfish captured at Manly. Sydney Mail
Oct 1926
15
Anon
Anon. (1926b). An 18 foot sawfish captured at Manly. Sydney Mail 13
October 1926, p. 15.
Sawfish captured. North Western Courier
Oct 1926
3
Anon
Anon. (1926c). Sawfish captured. North Western Courier 18 October 1926,
p. 3.
Monster sawfish. Daily Mercury
Nov 1929
4
Anon
Anon. (1929). Sawfish in a net. The Kyogle Examiner 1 November 1929, p. 2.
Anon. (1932). Monster sawfish. Daily Mercury 18 May 1932, p. 4.
Anon. (1935a). Sawfish about. Daily Mercury 9 April 1935, p. 4.
Large sawfish caught at Maclean. Macleay Argus
Oct 1935
4
Anon
Anon. (1935b). Sawfish caught. South Coast Bulletin 4 October 1935, p. 6.
Anon. (1935c). Large sawfish caught at Maclean. Macleay Argus 5 November
1935, p. 4.
17ft sawfish makes havoc. The Courier-Mail
Nov 1938
4
Anon
Anon. (1938). 17ft sawfish makes havoc. The Courier-Mail 11 November
1938, p. 4.
Large sawfish caught. Daily Mercury
Oct 1939
Anon
Anon. (1939). Large sawfish caught. Daily Mercury 5 October 1939, p. 4.
Anon. (1950). Sawfish. Fisherman's Luck and Fair Sport 1(6), 8.
Anon. (1926a). Harpooned. 18 ft sawfish caught at Manly. The Daily Telegraph
Jun 1902
1
Anon
Anon. (1902). A monster sawfish. Darling Downs Gazette 17 June 1902, p. 3.
Anon. (1923). Sawfish weighing 21/2 tons. The Register 10 March 1923, p. 5.
Anon. (1926a). Harpooned. 18 ft sawfish caught at Manly. The Daily
Telegraph 11 October 1926, p. 1.